System Performance Enhancements

The following system performance features and enhancements have been
added to the Solaris 10 5/09 release.

Large Segment Offload Support for Intel PCI Express
10Gb NIC Driver

This feature introduces Large Segment Offload (LSO) support for the ixgbe driver and some ixgbe driver bug fixes.
LSO is an important feature for NIC, especially for 10-Gb NIC. LSO can offload
the segmentation job on Layer 4 to the NIC driver. LSO improves transmit performance
by decreasing CPU overhead. This feature is enabled by default.

Solaris Power Aware Dispatcher and Deep C-State Support

This feature includes the following enhancements:

Event driven CPU power management – On systems that
support Dynamic Voltage and Frequency Scaling (DVFS) by Solaris, the kernel
scheduler or dispatcher will schedule threads across the system's CPUs in
a manner that coalesces load, and frees up other CPUs to be deeply power managed.
CPU power state changes are triggered when the dispatcher recognizes that
the utilization across a group of power manageable CPUs has changed in a significant
way. This eliminates the need to periodically poll CPU utilizations across
the system, and enables the system to save more power when CPUs are not used,
while driving performance when CPUs are used. Event driven CPU power management
is enabled by default on systems that support DVFS. This feature can be disabled,
or the legacy polling-based CPU power management can be used through
the cpupm keyword in power.conf(4).

Support for Deep Idle CPU Power Management or deep C-state
support on Intel Nehalem-based systems – The project also adds
Solaris support for Deep C-states on Intel Nehalem-based systems. This
support enables unused CPU resources to be dynamically placed in a state where
they consume a fraction of the power consumed in their normal operating state.
This feature also provides Solaris support for the power saving feature, as
well as the policy implementation that decides when idle CPUs should request
deep idle mode. This feature will be enabled by default where supported, and
can be disabled through the cpu-deep-idle keyword in power.conf(4).

Observability for Intel's Turbo Mode feature – Intel
Nehalem-based systems have the ability to raise the operating frequency
of a subset of the available cores when there is enough thermal headroom to
do so. This ability temporarily boosts performance, but it is controlled by
the hardware and transparent to software. Starting with the Solaris 10 5/09 release,
a new kstat module observes when the system is entering
the turbo mode and at which frequency it operates.